Screw-threading machine



July 10, 1951 Filed May 25. 1947 K. KUNZI SCREW THREADING MACHINE 2 Sheets-Sheet 1 K. KUNZI SCREW THREADING MACHINE Jul 10, 1951 Z-Sheets-Sheet 2 Filed May 25, 1947 Patented July 10, 1951 SCREW- THREADING MAOHIN E Karl Kiinzi, Schafihausen, Switzerland, assignor to Aktiengesellschaft der Eisenund Stablwerke vormals Georg Fischer, 'Sch'aifhausen,

Switzerland Application May 23, 1947, Serial No. 750,033 In Switzerland May 27, 1946 2 Claims. 1

My present invention relates to screw-threading machines comprising a chaser carrier (die head, die block or chuck) rotatable together with its spindle and axially displaceable and movable chasers provided with grooves in which the curved lugs or dogs of a cam disc are engaged, which disc, while rotatable relative to said carrier, is taking part in an axial movement thereof; and the hub of said disc is provided with a dog which is engaged in a groove of a bush which follows a rotary, but not an axial movement of the chaser-carrier spindle.

In accord with the essence of the present invention, the said grooved bush is given an additional rotation relative to the rotating chaser carrier for the purpose of additionally rotating the said cam disc and thus lifting the chasersafter finishing the screw-threading operationfrom the work. Such additional rotation is brought about by means of a key which is longitudinally displaceable relative to the chaser-car rier spindle and which is engaged in a skew groove of the said bush.

Various forms of the invention are illustrated by way of example, in the accompanyin drawings, in which Fig. 1 shows a vertical section through the screw-threading machine,

Fig. 1a. is a face view of a cam disc,

Fig. 2 a horizontal section on line AA in Fig. 3,

Fig. 3 a vertical section, at right angles to that of Fig. 1, on line B-'B in Fig. 2,

Fig. 4 a regional horizontal section, in larger scale, on line C-C of Fig. 3,

Fig. 5 a fragment of Fig. 4, wherein the individual elements, however, occupy a modified relative position,

Fig. 6 a component machine part adapted as grooved bush in front elevation,

Fig. '7 on one hand the rotation of the said grooved bush by means of an axially displaceable key and, on the other hand, the engagement of the dog of a grooved disc which actuates the chasing cutters, in a groove of said grooved bush,

Fig. 8 a second form of gear for longitudinally displacing the said key, in top plan view,

Fig. 9 a third form of gear for longitudinally displacing the said key, also in top plan View,

Fig. 10 the grooved bush as applied in the gear shown in Fig. 9, comprising a single skew roove and rotatable by a dog of an axially displaceable key, the dog of a grooved disc (which actuates 2 the chasing cutters) being engaged in the said skew groove, v

Fig. 11 a front elevation of the said grooved disc,

Fig. 12 schematically illustrated a fourth orm of gear for displacing the said key, in which further the gear for longitudinally displacing the chaser-carrier spindle is modified over the gear mentioned before; and

Fig. 13 is a vertical section of a modified detail.

Radially displaceable chasers 4 are mounted in the head or carrier l which is keyed to the spindle 3 which is rotatable in'the casing 2. Chasers i are displaced by known means such as cams 4" arranged oncam disc 4" (Fig. 1a) a cam disc which is rotatable relative to head I, and which, however, is so connected to the latter as to follow an axial displacement thereof. The cam-disc hub 5 projects beyond the rear side of head I and surrounds a grooved bush 6 which is rotatable relative thereto. Bush 6 is mounted rotatably on a bush 1 which in its turn is mounted rotatably in casing 2 and is secured against axial displacement relative to the latter. Grooved bush 6 is secured against axial displacement by a spring ring 8 housed in an annular groove of bush F. A radially projecting guide rail 9 is provided on spindle 3 of head I and engages in a longitudinal groove of bush 1 so that the latter will participate in any rotation of spindle 3, but so as to permit axial displacement of the spindle and head relative to bush 1. The bush l, further, is provided with a second longitudinal groove in which a key 10, abutting against spindle 3 is slidably guided. The forward end of key I0 is provided with a radial lug H which projects through a slot l2 (forming a continuation of the said second groove) in the cylindrical wall of bush 1, and is engaged in an inner oblique groove l3 of grooved bush 6 (Figs. 1, 6 and 7).

Cam-disc hub 5 is provided with a peripheral slot in which is adjustably, on its inner circumference, located a radially inwardly projecting dog M. The dog may be locked in different positions of saidv slot by means of a set screw l5. Dog H! is engaged in an obliquely extending groove It provided on the periphery of grooved bush 6.

A vise I! is provided in front of chaser-carrier I for the purpose of clamping the work to be screw-threaded. Spindle 3 and chaser-carrier I then is rotated and axially moved toward vise ll, whereby the cam disc also is displaced axially (see arrow ll in Fig. 7). In such latter displacement, however, dog l4 (moving in oblique groove I6 of bush 6) brings; about a rtation of cam-disc hub 5 (see arrow IS in Figs. 6, '7), and the latter displaces chasers 4 radially. Such latter displacement during the axial displacement of spindle 3, produces tapered threads on the work. During the cutting operation, key l|l--the lug ll of which acts as catch for grooved bush 6 in the rotary senseis not moved longitudinally. When the cutting operation has been finished, key I0 is longitudinally displaced (see Fig. 7) so that its lug H (which slides in the skew groove l3 of grooved bush 6) brings about an additional rotation of bush 6 and camdisc hub 5 (see arrow I3 in Figs. 6, 7) so that chasers 4 momentarily are moved still further radially outward, i. e. lifted from the work. Spindle 3 then continues its rotation and, with carrier is moved to the rear into its initial position. Durin such rearward movement, key In remains in the advanced position, and is also rearwardly displaced only when spindle 3 has practically completed its return movement. Chasing cutters 4 then will have regained their initial or starting position.

The following gear is provided for imparting a rotation and an axial displacement to spindle 3, and a separate axial displacement to key It].

A driving shaft is journaled in casing 2, and an elongated pinion 2| is fixedly keyed thereon. A large spur wheel 22 is secured by a pin to the hub of a. portion 23 of a claw coupling, which portion is freely revolvable and axially displaceable on spindle 3, and is in mesh with pinion 2|. The other coupling portion 24 secured by 'a pin to spindle 3. A sleeve-like slip ring 25 is mounted loosely revolvably 0n the loose coupling portion 23, and on its periphery is provided with a longitudinal groove 25 (Figs. 4, 5). A guide rail 21, by means of which slip ring 25 is prevented from rotating, is secured to casing 2 and is engaged in groove 26. A rack 28 (Fig. 2) is provided on slip ring 25, and is in mesh with a pinion '29 (Fig. 3) which is pinned to a vertical shaft 30 journalled in casing 2. Shaft 3|) may be rotated,

by means of a hand lever 3| (the hub 32 of which is secured on shaft 36 against rotation), so as to move slip ring 25 longitudinally by means of pinion 29. r

The following gear (Figs. 4, 5) is provided for preventing a longitudinal displacement of spindle 3, until the claws of coupling 23-24 are in full mesh:

A latch 33 is guided in a radial slot of slip ring 25, and its parallel end faces 35 and 35 are angularly disposed with respect to the axis of spindle 3. The radially inner oblique face 34 contacts the surface of a frustum of a cone 36 provided on the fixed coupling portion 24. The radially outer oblique face 35 of latch 33in the disengaged position of the coupling-is engaged in a notch 31 of guide rail 27, which slot on one side has the same slope as face 35 of latch 33. When, now, slip ring 25, upon engaging claw coupling 23, 24, is so displaced as to move portion 23 toward portion 24, latch 33 is displaced radially inward over the slope of notch 31, and the fixed coupling portion '24, together with spindle 3 is prevented from moving axially, until latch 33 has bodily moved out of notch 31.

The following arrangement (Figs. l-3) serves for longitudinally displacing key I0.

A thimble 38, at its top face adapted as a D tion of a cone coupling, is mounted loose on vertical shaft 3|), and its hub is mounted rotatable in the top portion of casing 2. The bottom face of the said hub abuts against a shoulder of shaft 30. The bottom face of hub 32 of hand lever 3| is adapted as the other portion of the said cone coupling. Shaft 33 projects beyond hub 32, and its terminal portion is provided with threads which are engaged by a nut 39 provided with a handle. When nut 33 is slacked thimble 38 may be turned relative to hub 32 or shaft 30 respectively, and be coupledby a subsequent tightening of nut 33 and in any desired angular position-to hub 32 of lever 35. In order to permit of controlling the mutual angular position, a scale 48 is provided on thimble 3B, and an index 4| on hub 32 of lever 3i. A second hand lever 42, provided on body 38, permits of turning the latter relative to hub 32. The bottom face of thimble 38, is provided with a stop 43 adapted to abut against a counterstop 44 provided on the top face of the hub of an arm 45 which is mounted freely rotatable on shaft 30. Arm 45 is biased by a tension spring 48 to contact an abutment 41. Arm &5, further, is provided with a stop 33 for a detent 43 of a lever 50 which is pinned to a vertical shaft 3| mounted rotatable in casing 2. A tension spring 52,- anchored at one end on arm 45 and at the other end to lever 50, biases the latter to turn counterclockwise. Lever 53, however, is prevented from such turning as long as its detent 49 is contacting stop 48 of arm 45. A segmental gear wheel 53 secured by pin means to shaft 5|, and meshes with a grooved wheel which is mounted axially displaceable' on spindle 3. Wheel 54 is rigidly secured to key If! so that, when turning gear segment 53 by lever 58, key it is longitudinally displaced. The coun terclookwise rotation of lever 50 is limited by means of an arm 55 which abuts against casing 2.

When hand lever 3| is turned clockwise, pinion 29 pinned to shaft 33 brings about a displacement of slip ring 25. During such displacement, clawcoupling portion 23 first is moved toward cou pling portion 24 which is mountedfast on spindle 3. After the claw coupling 23,-24 has been engaged, slip ring 25 and spindle 3 are moved in the direction of vise so as to screwthread on the work. After the desired length of threads has been obtained, stop 43 of body 38 abuts against counterstop 44 of arm 45 so that the latter swings clockwise, until stop 48 releases detent 49 of lever 56, and the latter, biased by spring 52, swings counterclockwise, thus raising the chasing cutters off the threads cut. The space 53 between stop 43 and counterstop 44 (Fig. 2) is essential for the length of the threads to be cut. The size of space 56 is changed by turning and then securing thimble 38 relative to hub 32 of lever 3!, as described above. Lever 50 is restored into locking position by means of a restoring lever 51 secured to shaft 30 and which, when turning lever 3| counterclockwise and immediately before completing the rearward displacement of spindle 3, abuts against lever 50 and swings the latter clockwise, until its detent 49 again is engaged in the rear of stop 48 of arm 45.

The arrangement, as described above, comprising a cone coupling for'establishing a connection between the elements 32 and 38, which connection is secured against relative rotation, also may be replaced by an arrangement as shown in Fig- 13. In the latter, hub 32 of hand lever 3| is pinned. to vertical shaft 30, and possesses a circular disc 58, on the circumference of which spaced notches 5 9 are provided. The latter may beengaged, as

attain;

5. desired by a set screw 69 provided in an arm 8| of thimble 38 which is rotatable relativeto. hub 32 In the embodiment described above, the grooved bush 8 comprises two skew grooves l3, IE5. (Figs. 6, '7). Bush 6, however, also may have only one skew groove 63, as shown in Figs. 10 and 11. In the latter, 62 is the grooved bush, and 63 the inner skew groove in which lug ll of key In and dog l4 of cam-disc hub 5 are engaged. When cutting the tapered threads, cutter-carrier I is moving forward, as indicated by arrow 64. in Fig. 10. Dog l4 of cam-disc hub 5, slides in groove 63.013 grooved bush 82; sov that hub 5 is rotated relative to the latter, as indicated by the arrows 65 in Figs. l and 11. After the threads have been cut, key I0 is moved backward, as indicated by the arrow on key ID in Fig. 10. Lu ll of key In then slides in groove 63 of bush 62, and rotates the latter relative to spindle 3, as indicated by the arrow 66 in Figs. 10 and 11, thus moving the chasing cutters 4 radially outward.

In the arrangement described with reference to Figs. 10 and 11, the backward movement of key In is brought about by means of the device shown in Fig. 9, in which the parts and portions corresponding to the embodiment described first, have like reference numerals. Lever 61, mounted loose on shaft 38, is provided with a stop 44, on one face, which may be contacted by the counterstop 43 of body 38 so that lever 61, when continuing the rotation of thimble 38 or hand lever 3| respectively takes part in such rotation. A link 69 at one end is pivoted at 68 to lever 61 and, at its other end, to a lever H at 70. Lever 1| is rotatable on a pivot 12 fastly secured to casing 2. The free end of lever II is provided with a slip ring which is engaged in a sleeve 13 rigidly secured to key In and thus longitudinally displaceable on spindle 3. When cutting threads, hand lever 3| here also is swung clockwise so as to engage spindle 3, and then axially moved forward for cutting the threads onto the work. Shortly before reaching the length of threads desired, stop 43 of thimble 38 abuts against counterstop 44 of lever B! so that the latter, as well as lever 1|, now also is rotated. The rotation of lever H is opposite to that of lever 81 so that key I8 is moved backward, and the chasing cutters raised off the threads cut. The return, i. e. the forward movement of key 8 shortly before completing the rearward stroke of spindle 3, by swinging hand lever 3| counterclockwise, here also is brought about by a restoring lever secured to shaft 30, here designated by 14 which, for the purpose of swinging lever backward, abuts against an arm I of lever l I.

Fig. 8 shows a simplified embodiment of the arrangement for displacing key it], which may be used in place of the arrangement illustrated in Fig. 2, corresponding parts and portions having the same reference numerals. A slip-ring sleeve 16 is fastly secured to key I ll, and thus longitudinally displaceable with the latter on spindle 3. Sleeve 16 is engaged by a slip-ring which is connected with the end of an arm H which is pivoted at 18 to case 2. Arm 45 is provided with a lug 19 which abuts against arm 11 so that the latter, when arm 45 swings clockwise, is swung counterclockwise, and key I8 is displaced forward on spindle 3. When hand lever 3| is swung counterclockwise, restoring lever 51 (pinned to shaft 30) will abut-before spindle 3 has been completely moved backwardagainst a lug provided on arm 11, so as to swing the latter clockwise and displace key |0 rearwardly.

In the embodiment schematically shown in Fig. 12., I denotes the chaser carrier, 3 the rotatable and longitudinally displaceable spindle to which carrier is fastly secured, It the key provided with, lug H and longitudinally displaceable on spindle. 3., and 22, the gear wheel for driving spindie 3. The. latter is axially displaced, by means of a hand lever 8| pivoted at to casing 2, by aid of a s1ip-ring engaged in a sleeve mounted on spindle 3. The design, however, also could be as. shown in Fig, 4, i. e. the slip-ring simultaneously may be used for actuating a claw coupling which engages. the gear wheel 22, which in such Case is mounted loosely rotatable on spindle 3,, to the. latter. A link 8.3 is pivoted at 82 on the machine casing, and its forked free end is in engagement with a slip rin 84 which is fastly mounted on key M. Lever 8i and link 83 are interconnected by a rod 85, one end of the latter is pivoted on 83 at. 88, and the other end passes through a bore in hand lever 8| and is provided with a head 8'! against which lever 8! may abut. A displaceable dog 88 is mounted on rod 85. A stationary stop 89 limits the counterclockwise swing of lever 8|. Pivots 88 and $2 are so positioned that levers 8| and 83 swing in opposition. A stationary stop 98 serves for limiting the counterclockwise swing of link 83. According to the position of dog 83, hand lever 8| swings clockwise through a greater or smaller angle, and spindle 3 simultaneously is moved forward over a corresponding distance before lever 8| abuts against dog 88. Upon such latter abutment, link 83 is SWlll'lg counterclockwise, until arrested by stop 88. During such swinging movement, key I0 is displaced forward so that its lug rotates grooved bush 6 relative to spindle 8, and the chasin cutters are raised from the threaded portion of the work. When hand lever 8| is swung backward, counterclockwise, and spindle 3 thus is rearwardly displaced, key I8 remains in its advanced position, until hand lever 8| contacts head 8'! of rod 85, upon which-when lever 8| is swung still further-link 83 is swung clockwise, and key 8 thus is displaced rearwardly. Dog 88 also could be mounted stationary on rod 85, in which case hand lever 8| is provided with an adjustable dog on the side facing dog 88 to permit of varying the angular deflection of lever 8|.

What I claim and desire to secure by Letters Patent is:

1. A screw-threading machine comprising a rotatable and axially movable spindle, a chaser carrier head mounted on said spindle for rotation and axial movement together with the spindle, a plurality of radially adjustable chasers mounted in said head and provided each with a groove, a cam disc mounted for movement with said carrier head and angularly movable relatively to the head, means on said cam disc engaging said grooves of the chaser to provide for radial movement of the chasers upon relative angular movement between said head and said cam disc, said cam disc carrying a hub member, a helically grooved bush rotatably mounted in said hub member, said bush being axially fixed but rotatable together with and relatively to said spindle, a dog on said hub member and engaging a helical groove in said bush, whereby the cam disc is angularly displaced upon axial movement of said spindle, a key carried by said spindle and longitudinally movable relatively to the spindle, said key having a lug slidably engaged in a helical groove of said bush, and means acting on said key upon completion of a thread cutting operation to longitudinally displace the key and provide for additional angular movement of said bush, hub member and cam disc relatively to the chaser head to lift the chaser off the work.

2. In a screw-threading machine having rotatable and axially movable chaser carrier head and driving spindle therefor, a plurality of radially adjustable chasers carried by said head, a cam disc disposed coaxially with said head and spindle for controlling the radial position of said chasers, said cam disc being angularly movable relative to said chaser carrier head, a hub member on said cam disc, a circumferentially adjustable dog carried by said hub member, a rotatable helically grooved bush mounted on said hub member, said dog on the hub member being engaged in a helical groove of the bush, whereby said cam disc i angularly displaced upon axial movement of said spindle, a key carried by said spindle and movable longitudinally thereof, one end of said 20 key being slidably engaged in a helical groove of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 180,869 Green Aug. 8, 1876 FOREIGN PATENTS Number Country Date 1,949 Great Britain July 27, 1865 

